Search

We use the SU(5) model to show the presence in grand unified theories of an electroweak monopole and a magnetic dumbbell ("meson") made up of a monopole-antimonopole pair connected by a Z-magnetic flux tube. The monopole is associated with the spontaneous breaking of the weak SU(2)L gauge symmetry by the induced vacuum expectation value of a heavy scalar SU(2)L triplet with zero weak hypercharge contained in the adjoint Higgs 24-plet. This monopole carries a Coulomb magnetic charge of (3/4)(2π/e) as well as Z-magnetic charge, where 2π/e denotes the unit Dirac magnetic charge. Its total magnetic charge is √3/8(4π/e), which is in agreement with the Dirac quantization condition. The monopole weighs about 700 GeV, but because of the attached Z-magnetic tube it exists, together with the antimonopole, in a magnetic dumbbell configuration whose mass is expected to lie in the TeV range. The presence of these topological structures in SU(5) and SO(10) and in their supersymmetric extensions provides an exciting new avenue for testing these theories in high-energy colliders. [ABSTRACT FROM AUTHOR]

We analyze the adjoint field inflation in supersymmetric (SUSY) SU(5) model. In minimal SUSY SU(5) hybrid inflation monopoles are produced at the end of inflation. We therefore explore the nonminimal model of inflation based on SUSY SU(5), like shifted hybrid inflation, which provides a natural solution for the monopole problem. We find that the supergravity corrections with nonminimal Kähler potential are crucial to realize the central value of the scalar spectral index ns≃0.96 consistent with the 7 yr WMAP data. The tensor to scalar ratio r is quite small, taking on values r≲10-5. Because of R symmetry massless SU(3) octet and SU(2) triplet supermultiplets are present and could spoil gauge coupling unification. To keep gauge coupling unification intact, light vectorlike particles are added which are expected to be observed at LHC. [ABSTRACT FROM AUTHOR]

We present ψ′MSSM, a model based on a U(1)ψ′ extension of the minimal supersymmetric standard model. The gauge symmetry U(1)ψ′, also known as U(1)N, is a linear combination of the U(1)χ and U(1)ψ subgroups of E6. The model predicts the existence of three sterile neutrinos with masses ≳0.1 eV, if the U(1)ψ′ breaking scale is of order 10 TeV. Their contribution to the effective number of neutrinos at nucleosynthesis is ΔNν ≃ 0.29. The model can provide a variety of possible cold dark matter candidates including the lightest sterile sneutrino. If the U(1)ψ′ breaking scale is increased to 10³ TeV, the sterile neutrinos, which are stable on account of a Z2 symmetry, become viable warm dark matter candidates. The observed value of the standard model Higgs boson mass can be obtained with relatively light stop quarks thanks to the D-term contribution from U(1)ψ′. The model predicts diquark and diphoton resonances which may be found at an updated LHC. The well-known μ problem is resolved and the observed baryon asymmetry of the universe can be generated via leptogenesis. The breaking of U(1)ψ′ produces superconducting strings that may be present in our galaxy. A U(1) R symmetry plays a key role in keeping the proton stable and providing the light sterile neutrinos. [ABSTRACT FROM AUTHOR]

We show how successful supersymmetric hybrid inflation is realized in realistic models where the resolution of the minimal supersymmetric standard model µ problem is intimately linked with axion physics. The scalar fields that accompany the axion, such as the saxion, are closely monitored during and after inflation to ensure that the axion isocurvature perturbations lie below the observational limits. The scalar spectral index n s ≃ 0.96 - 0.97, while the tensor-to-scalar ratio r, a canonical measure of gravity waves, lies well below the observable range in our example. The axion domain walls are inflated away, and depending on the axion decay constant f a and the magnitude of the µ parameter, the axions and/or the lightest supersymmetric particle compose the dark matter in the Universe. Nonthermal leptogenesis is naturally implemented in this class of models. [ABSTRACT FROM AUTHOR]